What reportedly happened: The pilot reported that, after a normal landing, the airplane suddenly veered to the left. He applied right rudder and right brake, but couldn’t regain control. The left main landing gear collapsed, and the left wing hit the ground. The airplane went off the runway onto a grassy area.

The post-accident examination revealed that the left main landing gear drag link had separated at the junction of the upper and lower drag links, and the landing gear strut had folded forward. The drag link appeared to be the original part installed during manufacture of the airplane in 1950. Examination of the separation surfaces on the drag link revealed that the drag link fractured due to over-stress. Most of the fracture surface appeared to be newly created indicating the majority of the over-stress fracture occurred at the time of the landing. Investigators determined that the fracture had occurred at an earlier time. The pilot reported that the landing gear was most recently inspected during the annual inspection about one month before the accident with no discrepancies noted. A small crack corresponding to the corroded portion of the fracture surface was likely present on the drag link at the time of this inspection, but it was not discovered.

Probable cause: The failure of the left main landing gear drag link as a result of over-stress fracture. Contributing to the accident was maintenance personnel’s failure to detect a small crack in the left main landing gear drag link during the most recent annual inspection.